Technical Abstract:
Forage kochia (K. prostrata ssp. virescent cv. 'Immigrant') is native to the arid and semiarid regions of Central Eurasia. It was introduced into U.S. in 1966 as PI 314929 and released as a perennial forage shrub in 1984. Kochia americana is a perennial native to U.S., whereas K. scorparia is an introduced annual species that became a weed. To assess both the breeding potential and the possibility of genetic contamination, genome relationships among the three species were analyzed using random amplified polymorphic DNA (RAPD) markers. Seventy decamer random primers yielded 458 polymorphic bands from nine accessions of K. americana, 20 accessions of K. prostrata, and seven accessions of K. scoparia. Fifty-four species-specific RAPD markers each were identified for K. americana and K. prostrata. Eighty-two RAPD markers were specific to K. scoparia. Based on the presence or absence of informative RAPD markers in any subsets of the complete RAPD database, the three species grouped into three distinct clusters in a NTSYSpc2.01b generated dendrogram. The relative positions of the three clusters varied depending on the data subset. Cophenetic similarity coefficient values were 0.44 between clusters of K. americana and K. prostrata, and 0.38 between the cluster of these two species and that of K. scoparia, when all 458 markers were analyzed as a single data-set. These relationships are congruent with those based on GISH. The three kochia species have so distantly-related genomes that gene introgression between species would be rare.